In the display industry, liquid crystal displays (LCDs) defeated traditional market leader, cathode-ray tubes, and plasma displays and have become the current mainstream in the development of flat-panel displays. The displaying principle of LCDs is to make use of dielectric anisotropy of liquid-crystal molecules. By applying an external electric field, the arrangement of liquid-crystal molecules changes, enabling various photoelectric effects in liquid-crystal thin films. As technologies progress, wearable and mobile products have become more popular. This trend also applies to the LCD industry. Presently, the requirements for product specifications in the LCD industry include lightness, thinness, lower radiation, and higher resolution.
Because the liquid crystals in LCDs do not emit light, backlight modules are required for LCDs to display images. Depending on the location of the light source, backlight modules can be further classified into direct and edge lighting types. Nonetheless, no matter what type of backlight module, as the light source, such as LEDs, emits light into the light-guiding plate, light enters the light-guiding plate by refraction, which dissipates photoenergy from the light source. In addition, backlight modules still include light enhancer, reflector, and diffuser stacked on and below the light-guiding plate. The stacked structure further increases the interfacial reflection of light at the air interface. The reflected light will overlap on the display area of a product and result in negative effects including white blooming and reduction in contrast. In order to solve the problem, a reflective LCD has been developed in the LCD industry.
Reflective displays use bump structures having reflective efficacy to reflect ambient light for illuminating the screen. In generally, if the bumps in the bump structure are smooth, the concentrating property of the reflected light is greater, which favors to front viewing. On the contrary, if the bumps of the array bump structure are sloped, wide-angle light can be received and reflected, which favors to wide-angle viewing. Thereby, in addition to saving backlight modules, the power consumption of backlight modules can be saved as well in reflective displays. Besides, the purpose of light and compact design can be achieved accordingly. Some small reflective LCD can be even driven by batteries alone. Hence, reflective displays are quite suitable for portable and mobile products. As the market demands increase, technological development for reflective LCDs is urged.
The current reflective display technology can be further categorized in reflective and transflective types. The reflective type uses external light sources for providing light to displays. Contrarily, the transflective type uses a backlight system to supplement insufficient ambient light. In other words, when the ambient light is sufficient, both the reflective and transflective types need no built-in light source and thus achieving the efficacy of saving power. Nonetheless, reflective displays still have some drawbacks. For example, no matter reflective or transflective type, a layer of bump structure should be fabricated for reflective or reflective/transmissive purposes. Unfortunately, under a single photolithography step, the bump angles of the array bump-structure layer in all pixels of a display panel are identical. It is difficult to cover concentrative and wide-angle properties. If different bump conditions are provided in a single pixel structure, more photolithography steps should be performed to different regions. This would add fabrication steps and thereby substantially increasing process time and costs.
Accordingly, the main purpose of the present invention is to provide an LCD module, which comprises a plurality of array bump-structure layers. In addition, only by a single photolithography step, bumps of the array bump-structure layers having different sloping conditions can be fabricated, which reduces fabrication steps as well as increasing process yield. Moreover, according users' requirements, the present invention can even further reflect merely the light from a specific angle.